# Energy Conservation Program for Consumer Products: Test Procedure for Residential Central Air Conditioners and Heat Pumps

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2010-12271

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** June 2, 2010
- **Citation:** 75 FR 31224

## Text

DEPARTMENT OF ENERGY
10 CFR Part 430
[Docket No. EERE-2009-BT-TP-0004]
RIN 1904-AB94
Energy Conservation Program for Consumer Products: Test Procedure for Residential Central Air Conditioners and Heat Pumps

AGENCY:

Office of Energy Efficiency and Renewable Energy, Department of Energy.

ACTION:

Notice of proposed rulemaking and public meeting.

SUMMARY:

The U.S. Department of Energy (DOE) proposes amendments to its test procedure for residential central air conditioners and heat pumps. The proposed amendments would add requirements for the calculation of sensible heat ratio, incorporate a method to evaluate off mode power consumption, and add parameters for establishing regional measures of energy efficiency. DOE will hold a public meeting to receive and discuss comments on the proposal.

DATES:

DOE will hold a public meeting in Washington, DC on Friday, June 11, 2010 from 9 a.m. to 4 p.m. The purpose of the meeting is to receive comments and to help DOE understand potential issues associated with this proposed rulemaking. DOE must receive requests to speak at the meeting before 4 p.m. Friday, June 4, 2010. DOE must receive a signed original and an electronic copy of statements to be given at the public meeting before 4 p.m. Friday, June 4, 2010.

DOE will accept comments, data, and other information regarding this notice of proposed rulemaking (NOPR) before or after the public meeting, but no later than August 16, 2010. See section V., “Public Participation,” of this NOPR for details.

ADDRESSES:

The public meeting will be held at the U.S. Department of Energy, Forrestal Building, Room 8E-089. You may submit comments, identified by docket number EERE-2009-BT-TP-0004 and/or Regulation Identifier Number (RIN) 1904-AB94, by any of the following methods:

•
Federal eRulemaking Portal http://www.regulations.gov.:
Follow the instructions for submitting comments.

•
E-mail: RCAC-HP-2009-TP-0004@ee.doe.gov.
Include the docket number EERE-2009-BT-TP-0004 and/or RIN number 1904-AB94 in the subject line of the message.

•
Postal Mail:
Ms. Brenda Edwards, U.S. Department of Energy, Building Technologies Program, Mailstop EE-2J, 1000 Independence Avenue, SW., Washington, DC 20585-0121. Please submit one signed paper original.

•
Hand Delivery/Courier:
Ms. Brenda Edwards, U.S. Department of Energy, Building Technologies Program, 6th Floor, 950 L'Enfant Plaza, SW., Washington, DC 20024. Telephone: (202) 586-2945. Please submit one signed paper original.

Instructions:
All submissions must include the agency name and docket number or RIN for this rulemaking. For detailed instructions on submitting comments and additional information on the rulemaking process, see section V., “Public Participation,” of this document.

Docket:
For access to the docket to read background documents or comments received, visit the U.S. Department of Energy, 6th Floor, 950 L'Enfant Plaza, SW., Washington, DC 20024, (202) 586-2945, between 9 a.m. and 4 p.m., Monday through Friday, except Federal holidays. Please call Ms. Brenda Edwards at (202) 586-2945 for additional information regarding visiting the Resource Room. Please note: DOE's Freedom of Information Reading Room (Forrestal Building, Room 1E-190) no longer houses rulemaking materials.

FOR FURTHER INFORMATION CONTACT:

Mr. Wes Anderson, U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Program, EE-2J, 1000 Independence Avenue, SW., Washington, DC 20585-0121. Telephone: (202) 586-7335. E-mail:
Wes.Anderson@ee.doe.gov.

Ms. Francine Pinto, U.S. Department of Energy, Office of the General Counsel, GC-71, 1000 Independence Avenue, SW., Washington, DC 20585. Telephone: (202) 586-7432. E-mail:
Francine.Pinto@hq.doe.gov.

SUPPLEMENTARY INFORMATION:

I. Authority and Background

A. Authority

B. Background

II. Summary of the Proposed Rule

III. Discussion

A. Framework Comment Summary and DOE Responses

1. Test Procedure Schedule

2. Bench Testing of Third-Party Coils

3. Defaults for Fan Power

4. Changes to External Static Pressure Values

5. Fan Time Delay Relays

6. Inverter-Driven Compressors

7. Addition of Calculation for Sensible Heat Ratio

8. Regional Rating Procedure

9. Address Testing Inconsistencies for Ductless Mini- and Multi-Splits

10. Standby Power Consumption and Measurement

B. Summary of the Test Procedure Revisions

1. Modify the Definition of “Tested Combination” for Residential Multi-Split Systems

2. Add Alternative Minimum External Static Pressure Requirements for Testing Ducted Multi-Split Systems

3. Clarify That Optional Tests May Be Conducted Without Forfeiting Use of the Default Value(s)

4. Allow a Wider Tolerance on Air Volume Rate To Yield More Repeatable Laboratory Setups

5. Change the Magnitude of the Test Operating Tolerance Specified for the External Resistance to Airflow
and the Nozzle Pressure Drop

6. Modify Third-Party Testing Requirements When Charging the Test Unit

7. Clarify Unit Testing Installation Instruction and Address Manufacturer and Third-Party Testing Laboratory Interactions

8. When Determining the Cyclic Degradation Coefficient C
D
, Correct the Indoor-Side Temperature Sensors Used During the Cyclic Test To Align With the Temperature Sensors Used During the Companion Steady-State Test, If Applicable

9. Clarify Inputs for the Demand Defrost Credit Equation

10. Add Calculations for Sensible Heat Ratio

11. Incorporate Changes To Cover Testing and Rating of Ducted Systems Having More Than One Indoor Blower

12. Add Changes To Cover Triple-Capacity, Northern Heat Pumps

13. Specify Requirements for the Low-Voltage Transformer Used When Testing Only Air Conditioners and Heat Pumps and Require Metering of All Sources of Energy Consumption During All Tests

14. Add Testing Procedures and Calculations for Off Mode Energy Consumption

15. Add Parameters for Establishing Regional Standards

a. Use a Bin Method for Single-Speed SEER Calculations for the Hot-Dry Region and National Rating

b. Add New Hot-Dry Region Bin Data

c. Add Optional Testing at the A and B Test Conditions With the Unit in a Hot-Dry Region Setup

d. Add a New Equation for Building Load Line in the Hot-Dry Region

16. Add References to ASHRAE 116-1995 (RA 2005) for Equations That Calculate SEER and HSPF for Variable Speed Systems

17. Update Test Procedure References to the Current Standards of AHRI and ASHRAE

IV. Regulatory Review

A. Review Under Executive Order 12866

B. Review Under the National Environmental Policy Act

C. Review Under the Regulatory Flexibility Act

D. Review Under the Paperwork Reduction Act

E. Review Under the Unfunded Mandates Reform Act of 1995

F. Review Under the Treasury and General Government Appropriations Act, 1999

G. Review Under Executive Order 13132

H. Review Under Executive Order 12988

I. Review Under the Treasury and General Government Appropriations Act, 2001

J. Review Under Executive Order 13211

K. Review Under Executive Order 12630

L. Review Under Section 32 of the Federal Energy Administration (FEA) Act of 1974

V. Public Participation

A. Attendance at Public Meeting

B. Procedure for Submitting Requests To Speak

C. Conduct of Public Meeting

D. Submission of Comments

E. Issues on Which DOE Seeks Comment

VI. Approval of the Office of the Secretary

I. Authority and Background

A. Authority

Title III of the Energy Policy and Conservation Act (42 U.S.C. 6291
et seq.;
EPCA or the Act) sets forth a variety of provisions designed to improve energy efficiency. Part A of Title III (42 U.S.C. 6291-6309) establishes the “Energy Conservation Program for Consumer Products Other Than Automobiles.” (This part was originally titled Part B; however, it was redesignated Part A in the United States Code for editorial reasons.) The program covers consumer products and certain commercial products (collectively “covered products”), including residential central air conditioners and heat pumps having rated cooling capacities less than 65,000 British thermal units/hour (Btu/h). (42 U.S.C. 6291(1)-(2), (21) and 6292(a)(3))

Under the Act, the overall program consists of testing, labeling, and Federal energy conservation standards. Manufacturers of covered products must use the test procedures prescribed under EPCA to measure energy efficiency, to certify to DOE that products comply with EPCA's energy conservation standards, and for representing the energy efficiency of their products. Similarly, DOE must use these test procedures when determining whether the equipment complies with energy conservation standards adopted pursuant to EPCA.

Section 323 of EPCA (42 U.S.C. 6293) sets forth generally applicable criteria and procedures for DOE's adoption and amendment of such test procedures. For example, the Act states that “[a]ny test procedures prescribed or amended under this section shall be reasonably designed to produce test results which measure energy efficiency, energy use * * * or estimated annual operating cost of a covered product during a representative average use cycle or period of use, as determined by the Secretary [of Energy], and shall not be unduly burdensome to conduct.” (42 U.S.C. 6293(b)(3)) DOE's existing test procedures for central air conditioners and heat pumps adopted pursuant to these provisions appear under Title 10 of the Code of Federal Regulations (CFR) part 430, subpart B, appendix M (“Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps”).

Further, if any rulemaking amends a test procedure, DOE must determine “to what extent, if any, the proposed test procedure would alter the measured energy efficiency * * * of any covered product as determined under the existing test procedure.” (42 U.S.C. 6293(e)(1)) If it determines that the amended test procedure would alter the measured efficiency of a covered product, DOE must amend the applicable energy conservation standard accordingly. (42 U.S.C. 6293(e)(2)) The amendments proposed in today's rulemaking will not alter the measured efficiency, as represented in the regulating metrics of SEER and HSPF. Thus, today's proposed test procedure changes can be adopted without amending the standards for SEER and HSPF.

On December 19, 2007, the President signed the Energy Independence and Security Act of 2007 (EISA 2007; Pub. L. 110-140), which contains numerous amendments to EPCA. Section 310 of EISA 2007 established that the Department's test procedures for all covered products must account for standby and off mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) DOE must modify the test procedures to integrate such energy consumption into the energy descriptor(s) for each product, unless the Secretary determines that “(i) the current test procedures for a covered product already fully account for and incorporate the standby mode and off mode energy consumption of the covered product; or (ii) such an integrated test procedure is technically infeasible * * * in which case the Secretary shall prescribe a separate standby mode and off mode energy use test for the covered product, if technically feasible. (42 U.S.C. 6295 (gg)(2)(A)) In addition, section 306(a) of EISA 2007 amended EPCA section 325(o)(6) to consider one or two regional standards for central air conditioners and heat pumps (among other products) in addition to a base national standard. (42 U.S.C. 6295(o)(6)(B)) EPCA 325(o)(6)(C)(i) requires that DOE consider only regions made up of contiguous States. (42 U.S.C. 6295(o)(6)(C)(i)) Accordingly, today's proposed test procedure rulemaking includes additions that specifically address sections 306 and 310 of EISA 2007.

B. Background

Most portions of the existing test procedure for central air conditioners and heat pumps were originally published as a final rule in the
Federal Register
on December 27, 1979. 44 FR 76700. DOE modified the test procedure on March 14, 1988, to expand coverage to variable-speed central air conditioners and heat pumps, to address testing of split non-ducted units, and to change the method for crediting heat pumps that provide a demand defrost capability. 53 FR 8304.

The next revision of the central air conditioners and heat pumps test procedure was published as a final rule on October 11, 2005, and became effective on April 10, 2006. 70 FR 59122. The October 2005 final rule provided a much needed updating to reference current standards, adopted improved measurement capabilities, and presented more detail on how to conduct the laboratory testing. The 2005 final rule also expanded coverage for equipment features previously not covered (
e.g.,
two-capacity northern heat pumps, heat comfort controllers, triple-split systems, etc.). During this revision process, the test procedure was significantly reorganized in an effort to improve its readability.

On July 20, 2006, DOE published a proposed rule to consider additional changes to the test procedure in response to issues interested parties submitted before the October 2005 publication of the final rule. 71 FR 41320. DOE determined that it was appropriate to consider additional modifications to the test procedure for the following reasons: (1) To implement test procedure revisions for new energy conservation standards for small-duct, high-velocity (SDHV) systems; (2) to address test procedure waivers for multi-split systems; and (3) to address interested parties' concerns about sampling and rating after new energy conservation standards became effective on January 23, 2006. (10 CFR 432.32(c)(2)) DOE issued a final rule adopting relevant amendments to the central air conditioner and heat pump test procedures on October 22, 2007, which became effective on April 21, 2008. 72 FR 59906. This latter final rule was published before EISA's implementation on December 19, 2007; therefore, the test procedures did not incorporate the requirements in sections 306 and 310 of EISA 2007.

While making changes necessary to comply with the amendments in EISA 2007, DOE is considering additional changes to the test procedure that were identified after finalizing the prior rulemaking.

II. Summary of the Proposed Rule

DOE proposes amendments to its test procedure for residential central air conditioners and heat pumps. The amendments would add calculations for determination of sensible heat ratio (SHR), would incorporate a method to evaluate off mode power consumption, and would add parameters for establishing regional measures of energy efficiency.

In addition to statutory requirements for amended test procedures, EISA 2007 has three separate provisions regarding the inclusion of standby mode and off mode energy use in any energy conservation standard that have bearing on the current test procedure rulemaking. First, test procedure amendments to include standby mode and off mode energy consumption shall not be used to determine compliance with standards established prior to the adoption of such test procedure amendments. (42 U.S.C. 6295(gg)(2)(C)) Second, standby mode and off mode energy use must be included into a single amended or new standard for a covered product adopted in a final rule after July 1, 2010. Finally, a separate standard for standby mode and off mode energy consumption is required if a single amended or new standard is not feasible. (42 U.S.C. 6295(gg)(3)(B))

In order to accommodate the above-mentioned first provision, DOE clarifies that today's proposed amended test procedure would not alter the measure of energy efficiency used in existing energy conservation standards; therefore, this proposal would neither affect a manufacturer's ability to demonstrate compliance with previously established standards nor require retesting and rerating of existing units that are already certified. These amended test procedures would become effective, in terms of adoption into the CFR, 30 days after the date of publication in the
Federal Register
of the final rule in this test procedure rulemaking. However, DOE is proposing added language to the regulations codified in the CFR that would state that any added procedures and calculations for determining off mode energy consumption and regional cooling mode performance being proposed in order to satisfy the relevant provisions of EISA 2007 need not be performed at this time to determine compliance with the current energy conservation standards. Subsequently, and consistent with the second provision above, manufacturers would be required to use the amended test procedures' off mode and regional cooling mode provisions to demonstrate compliance with DOE's energy conservation standards on the effective date of a final rule establishing amended energy conservation standards for these products that address off mode energy consumption and/or regional cooling mode performance, at which time the limiting statement in the DOE test procedure would be revised or removed. Further clarification would also be provided that as of 180 days after publication of a test procedure final rule, any representations as to the off mode energy consumption and regional cooling mode performance of the products that are the subject of this rulemaking would need to be based upon results generated under the applicable provisions of this test procedure. (42 U.S.C. 6293(c)(2)) A separate standard for off-mode energy consumption is required if a single amended or new standard is not feasible. (42 U.S.C. 6295(gg)(3)(B))

III. Discussion

The current standards rulemaking preliminary analysis for residential central air conditioners and heat pumps is ready for stakeholder review and comment. This preliminary analysis follows the first step in the standards rulemaking process, the release of the framework document (
http://www1.eere.energy.gov/buildings/appliance_standards/residential/pdfs/cac_framework.pdf
) and the subsequent June 12, 2008 public meeting. At and following this latter meeting, stakeholder comments were received, some of which apply to today's proposed test procedure.

In formulating today's notice of proposed rulemaking (NOPR), DOE considered these test procedure related comments and, where appropriate, proposed changes to the test procedure. Moreover, DOE responses to stakeholder comments are provided in the following subject areas:

1. Test Procedure Schedule

2. Bench Testing of Third Party coils

3. Defaults for Fan Power

4. Changes to External Static Pressure Values

5. Fan Time Delay Relays

6. Inverter-Driven Compressors

7. Addition of Calculation for Sensible Heat Ratio

8. Regional Rating Procedure

9. Address Testing Inconsistencies for Ductless Mini- and Multi-Splits

10. Standby Power Consumption and Measurement

Section III. A. provides a more in-depth discussion on those comments that questioned or disagreed with DOE's positions in the framework document.

Section III. B. provides a summary of the proposed changes to the test procedure, including

1. Modify the definition of “tested combination” for residential multi-split systems

2. Add Alternative Minimum External Static Pressure Requirements for Testing Ducted Multi-Split Systems

3. Clarify that Optional Tests May Be Conducted Without Forfeiting Use of the Default Value(s)

4. Allow a Wider Tolerance on Air Volume Rate to Yield More Repeatable Laboratory Setups

5. Change the Magnitude of the Test Operating Tolerance Specified for the External Resistance to Airflow and the Nozzle Pressure Drop

6. Modify Third-Party Testing Requirements when Charging the Test Unit

7. Clarify Unit Testing Installation Instruction and Address Manufacturer and Third-Party Testing Laboratory Interactions

8. When Determining the Cyclic Degradation Coefficient C
D
, Correct the Indoor-Side Temperature Sensors Used During the Cyclic Test to Align with the Temperature Sensors Used During the Companion Steady-State Test, If Applicable

9. Clarify Inputs for the Demand Defrost Credit Equation

10. Add Calculations for Sensible Heat Ratio

11. Incorporate Changes to Cover Testing and Rating of Ducted Systems Having More than One Indoor Blower

12. Add Changes To Cover Triple-Capacity, Northern Heat Pumps.

13. Specify Requirements for the Low-Voltage Transformer Used when Testing Coil-Only Air Conditioners and Heat Pumps and Require Metering of All Sources of Energy Consumption During All Tests

14. Add Testing Procedures and Calculations for Off Mode Energy Consumption

15. Add Parameters for Establishing Regional Standards

As part of today's rulemaking, DOE provides the specific proposed changes to 10 CFR part 430, subpart B, appendix M, “Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps.”

A. Framework Comment Summary and DOE Responses

A notation in the form “Southern Company Systems (SCS), No. 13 at p. 105” identifies a written comment DOE

has received and has included in the docket of this rulemaking. This particular notation refers to a comment (1) by the Southern Company Systems (SCS); (2) in document number 13 in the docket of this rulemaking; and (3) appearing on page 105 of document number 13.

1. Test Procedure Schedule

Several interested parties commented that DOE should consider the timeline necessary when modifying this test procedure, and how the publication of the test procedure coincides with publication of the revised standard. (Southern Company Systems (SCS), No. 13 at p. 105; Air-Conditioning, Heating and Refrigeration Institute (AHRI), No. 13 at p. 116; the American Council for an Energy Efficient Economy (ACEEE), No. 13 at p. 117; Trane, No. 13 at p. 123)

DOE is coordinating the publication timelines of both the test procedure and the amended standard. The test procedure NOPR will be open for public comments. DOE will then address those comments and publish a final test procedure rule. The associated standard will proceed concurrently with the test procedure rulemaking to maximize the time interval between the test procedure final rule and the revised energy standards final rule.

2. Bench Testing of Third-Party Coils

The Northeast Energy Efficiency Partnerships (NEEP) comment stated that test procedures should require laboratory/bench testing for independent coil manufacturers' (ICM) indoor units. (NEEP, No. 37 at p. 3) NEEP includes representatives from the Connecticut Office of Policy and Management, New Hampshire Office of Energy and Planning, Efficiency Maine, and Department of Energy Resources for the Commonwealth of Massachusetts.

As amended, EPCA makes all residential central air conditioners and heat pumps sold in the United States subject to specific testing, rating, minimum efficiency, and labeling requirements. These requirements apply to complete systems, including those split systems where the outdoor components are provided by one manufacturer, while the indoor components are provided by a separate manufacturer. The typical two-manufacturer split system is where the indoor unit is provided by an ICM and the outdoor unit is provided by an original equipment manufacturer (OEM). Because the ICM wants to advertise the performance of its indoor coils with various OEM outdoor units, the ICM is responsible for obtaining the system seasonal energy efficiency ratio (SEER) and heating seasonal performance factor (HSPF) ratings according to DOE requirements. In obtaining these ratings, the ICM can either test complete systems or use a DOE-approved alternative rating method (ARM) to calculate the rating. Approval of the ARM requires laboratory test results for complete systems, but inputs to the ARM may or may not require testing of just the indoor unit. (10 CFR 430.24)

Although DOE does not have the authority to regulate a component of an air conditioner or heat pump system, it does regulate the complete systems. The system ratings published by ICMs must be obtained in accordance with DOE requirements summarized above.

3. Defaults for Fan Power

A Joint Comment stated that the present rating method does not credit advanced air handler designs adequately because the default value is much lower than the average air handler energy use observed in the field. (Joint Comment, No. 25 at pp. 4, 6-7) According to the Joint Comment, a low default value for fan power reduces the incentive to improve fan efficiency. The Joint Comment includes representatives from ACEEE, Appliance Standards Awareness Project (ASAP), the California Energy Commission (CEC), the Northwest Power and Conservation Council (NPCC), and the Western Cooling Efficiency Center (WCEC).

Proctor Engineering Group (Proctor) stated that the inside coil fan energy needs to represent the median values from actual installations, and also provided input on the methodology for evaluating fan power based on air volume rate and equipment tonnage. (Proctor, No. 38 at p. 1)

NEEP stated that testing should be required for motors in actual operation and that the procedure should include provisions for testing while air handler fans are running. (NEEP, No. 37 at p. 3)

Split-system ducted air conditioners and heat pumps are primarily designed for two different applications. These applications depend on whether the air conditioner or heat pump is installed with a hot-air furnace and share a common duct system. Air conditioners and heat pumps not designed for installation with a hot-air furnace must contain a blower to circulate air through the indoor coil and ductwork. Systems that include the integral or modular indoor blower are typically referred to as blower-coil units. Coil-only units—air conditioners and heat pumps designed for installation with a hot-air furnace—rely on the furnace blower to circulate air through the indoor coil, ductwork, and the furnace section when the compressor and outdoor fan are operating.

The Joint Comment pertains to coil-only units, so discussion in the following paragraphs is limited to those products. This comment does not apply to blower-coil units within the test procedure because there is no required default assumption for the average air handler. With regard to the NEEP comment, the ratings for blower coil units already reflect the performance of the system's particular indoor blower. When blower coils are tested, the indoor blower operates, and its performance is accounted for in the measured system capacity and power consumption values and ultimately in SEER and HSPF.

A coil-only air conditioner or heat pump can be installed with a multitude of new and existing furnaces. The key considerations for matching a coil-only unit with a furnace are (1) the furnace blower's ability to provide the necessary air volume rate for the system; and (2) whether the outlet flange dimensions of the furnace are compatible with the inlet flanges on the indoor coil-only section of the air conditioner or heat pump. Another factor for field application is whether the overall height (length) of the furnace and coil-only indoor section will fit into the available building space.

The SEER and HSPF ratings represent the seasonal efficiencies of a complete, functioning air conditioner or heat pump system. However, coil-only split systems in laboratory testing are incomplete because a hot-air furnace is not part of the setup. Instead of the furnace blower, the exhaust fan in the test facility pulls air through the indoor unit of the coil-only system. The exhaust fan is located downstream of the test unit's indoor section, outlet instrumentation, and air volume measurement station. When the hot-air furnace and blower are removed from testing, the associated power consumption and measured cooling or heating capacity are adjusted to account for the hypothetical hot-air furnace blower. The Joint Comment asserted that the test procedure default value is too low and should require additional real-time blower testing. Proctor Engineering Group agreed and offered an alternative default equation based on data collected from actual installations.

Given the variety of furnaces within which a coil-only unit may be installed, the range of blower sizes and associated efficiency of a complete installed system are unknown. As a result, there are several options for calculating the assumed power and heat contributions for the hypothetical hot-air furnace

blower. To obtain a SEER (and for heat pumps, an HSPF) rating for each coil-only split system, the hot-air furnace blower receives a default value. According to the DOE test procedure, the hypothetical hot-air furnace blower contribution is expressed in terms of power (watts) and heat (Btu/h) per unit of air volume rate (in this case, 1,000 standard cubic feet per minute [scfm]).

Since it was issued in 1979, the DOE test procedure for central air conditioners and heat pumps has used the same default fan power and heat for rating coil-only air conditioners and heat pumps: 365 watts per 1,000 scfm and 1,250 Btu/h per 1,000 scfm. These default values result in the adjustment range from approximately 220 watts (750 Btu/h) for a 1.5-ton unit to approximately 730 watts (2,500 Btu/h) for a 5-ton unit.

The default value does not indicate the efficiency of blowers in furnaces; it simply provides a means of comparing products on a complete system basis. The long-standing default values represent a typical furnace blower while not being overly conservative. Changing the default values would shift the SEER and HSPF ratings, but the ranking among most comparably sized equipment would change minimally, if at all. DOE evaluated the worst-case scenario: multiple units with the same SEER calculated using the existing fan power and heat defaults, but with degradation coefficients (
C
D
) varying from 0.01 and 0.25, and capacities differing up to 10 percent. If the SEER calculation uses a higher default like 500 watts per 1,000 scfm (1,700 Btu/h per 1,000 scfm), the new SEER ratings would all decrease but lie within a range that spans less than 0.20 points (on the SEER rating scale). The minimal impact on the ranking lessens the need for better defaults. To determine whether higher default values better represent actual installations, DOE must address three questions:

• What data can accurately represent the typical installation?

• What coordination will ensure that blower coils and coil-only units are evaluated on a common basis?

• Should poor duct systems affect equipment ratings?

DOE expects that addressing these questions will require additional data collection, analysis, and input from interested parties. With minimal impact on altering the relative ranking among competing products combined with the need to answer the above questions, DOE chose not to propose alternative default values for the power and heat contribution of the hypothetical furnace blower used when calculating the SEER and HSPF for coil-only air conditioners and heat pumps.

4. Changes to External Static Pressure Values

A Joint Comment stated that the current assumed inches of water column (in wc) values are lower than those typically found in the field and unrealistically deemphasize the importance of fan efficiency as a part of overall system effectiveness. (Joint Comment, No. 25 at pp. 4, 6) The discrepancy often leads to less airflow in a field application, which generally improves latent (at the expense of sensible) capacity.

The Joint Utility Comment suggested that new test conditions for external static pressure and default fan power should be consistent with current field research findings. (Joint Utility Comment, No. 30 at pp. 1, 21) The Joint Utility Comment includes representatives from Pacific Gas and Electric Company (PG&E), Southern California Edison, Sempra Energy Utilities (Southern California Gas Company and San Diego Gas and Electric Company; hereafter “Sempra”), Sacramento Municipal Utility District, the Nevada Power Company, and Sierra Pacific Power.

DOE received a number of comments requesting that the minimum external static pressure levels be increased. (Florida Solar Energy Center (FSEC), No. 31 at p. 4; Sempra, No. 13 at p. 121; SCS, No. 39 at p. 2) Additionally, Proctor Engineering Group (Proctor) provided a formula for estimating the static pressure based on the rated cfm/ton (Proctor, No. 38 at p. 2).

Some split system and all single-package system air conditioners and heat pumps are sold with integral indoor blowers. Split systems with integral indoor blowers (
i.e.,
blower-coil units) may be designed for ducted or non-ducted installation. The integral indoor blower may be located either upstream (push-through configuration) or downstream (draw-through configuration) of the indoor refrigerant-to-air heat coil.

To mimic a field installation, single-package and blower-coil split air conditioners and heat pumps are laboratory tested with installed components to include the most restrictive filter(s), supplementary heating coils, and other equipment specified as part of the unit. The DOE test procedure allows testing of a ducted unit without an indoor air filter but requires a compensatory increase of 0.08 in wc for the minimum external static pressure requirement. Otherwise, the test procedure requires that the unit be installed and configured in accordance with the manufacturer's instructions.

The DOE test procedure requires that a minimum external static pressure be equaled or exceeded during the wet-coil cooling mode test. If this requirement is not met initially, the configuration of the indoor unit is incrementally changed (
e.g.,
switched to the next highest speed tap), and the wet-coil test is repeated until the measured external static pressure meets or surpasses the applicable DOE test procedure minimum value.

Since its issuance in 1980, the DOE test procedure for central air conditioners and heat pumps has used the same set of minimum external static pressure values (except for SDHV systems): 0.10 in wc for systems with a rated cooling capacity less than or equal to 28,800 Btu/h, 0.15 in wc for 29,000 to 42,500 Btu/h, and 0.20 in wc for 43,000 to 64,500 Btu/h. The laboratory static pressure measurement tries to account for the supply and return home or building duct system unit flow resistance.

Limited field testing reports and the general decline in the quality of installed duct systems (in part from the proliferation of the flexible duct) would support an increase in the minimum external static pressure. Efforts by building trades and code compliance communities to improve the quality of installed duct systems would support smaller increases in the minimum statics prescribed in the DOE test procedure. More field data would be helpful but would likely never be acquired to the level needed to provide a definitive basis for selecting new minimums. The greater impact of higher minimum external static pressures will be on lowering the SEER and HSPF of all units equally. Lacking a basis to propose new values or reference a consensus standard where alternatives to the current minimums are established, DOE chose not to propose an alternative to the existing minimum values as part of today's NOPR.

5. Fan Time Delay Relays

FSEC and SCS commented that the fan time delay relays should be disabled for the SEER test procedure. (FSEC, No. 31 at p. 3; SCS, No. 39 at p. 2)

Many air conditioners and heat pumps employ a fan-off delay feature on the indoor blower. This delay, which is usually active for both the cooling and heating modes, is used to extract stored energy from the indoor coil immediately after the compressor has cycled off. The indoor blower typically continues to operate for 45 to 90 seconds after the compressor cycles off.

The DOE test procedure seeks to evaluate the performance of central air conditioners and heat pumps without making the process overly burdensome or expensive. The test procedure includes optional cyclic tests used to quantify the degradation in performance from the system cycling (predominantly in field installation) compared with operating continuously (as in most laboratory tests). During these cyclic tests, the fan-off delay feature is not disabled. The evaluation thus accounts for an incremental increase in total delivered capacity at the expense of increased electrical energy consumption in extending the indoor blower operation.

Disabling the fan time delay from central air conditioners and heat pumps during the cooling season will prevent re-evaporation of moisture on the indoor coil and in the condensation pan. Substantial re-evaporation can occur if the indoor blower continues for an extended period after compressor shutoff. Because of this evaporative mechanism, continuous fan operation is discouraged during the cooling season. However, DOE is not aware of definitive data that show significant re-evaporation during short fan-off delays. Part of the data void is due to the challenge of measuring rapidly changing values (humidity and temperature) during the relatively short fan-off delay period. Because of this difficulty, the cyclic cooling mode test, used in establishing the SEER, is conducted at an indoor wet bulb (wb) temperature that results in a dry coil. This also explains why this test cannot be used to address the concern about re-evaporation.

In a related comment, Proctor recommended conducting the cooling mode cyclic tests with the indoor conditions set to the same values used for the steady-state tests, 80 degrees Fahrenheit (°F) dry bulb (db)/67 °F wb (Proctor, No. 38 at p. 2). Proctor stated that such a change to wet-coil cooling mode cyclic tests is well within the reach of today's measurement technologies.

DOE needs additional information to quantify the potential benefits of converting from dry-coil to wet-coil cyclic testing. DOE must evaluate any potential benefits relative to any laboratory upgrades that would be needed to achieve acceptably accurate and repeatable results across the industry, and the impact of changing the time required to run a cyclic test. DOE seeks data and information that would aid efforts to quantify the relative performance impact and associated expense of laboratory upgrades in combination with achievable measurement uncertainty. Until more is known about the impact of changing from the long-standing dry-coil tests to a wet-coil cyclic test, DOE has tentatively decided not to modify this test procedure to convert to wet-coil cyclic testing.

6. Inverter-Driven Compressors

Mitsubishi Electric and Electronics USA, Inc. (MEUS) commented that new systems incorporating inverter-driven compressor technology require a modification to the test procedure. (MEUS, No. 13 at p. 19)

Since 1988, the DOE test procedure has covered air conditioners and heat pumps with variable-speed compressors, single indoor units, and single outdoor units. The October 2007 final rule extended coverage to variable-speed multi-split systems. 72 FR 59906. Before DOE can offer a more substantive evaluation of the comment, DOE will need specific examples, including laboratory data, of how the test procedure fails to capture the performance characteristics of an air conditioner or heat pump that uses “new inverter-driven compressor technology.”

7. Addition of Calculation for Sensible Heat Ratio

The Joint Comment contended that the latent heat removal capability of CAC equipment should be measured under typical operating conditions, as opposed to high temperature conditions, and should be certified for all models sold in hot and humid climates. (Joint Comment, No. 25 at p. 4) FSEC expressed similar views and suggested that the latent heat ratio should be measured under different test conditions for single speed and multi-speed equipment. (FSEC, No. 31 at p. 2) Ice Energy suggested that the dehumidification capability of CAC equipment under hot and humid conditions be included in the standard, and any regional standard for the Southeast region should address this issue. (Ice Energy, No. 33 at p. 3) On the other hand, the Edison Electric Institute (EEI) wants dehumidification capability to be included in the standards for all regions. (EEI, No. 20 at p. 4) SCS stated that for hot and humid climates, a higher dehumidification capacity should be incorporated in the standard. (SCS, No. 13 at p. 42) SCS also stated that any regional air conditioning standard should provide for minimum dehumidification performance that should be measured at normal operating conditions and not at a higher temperature like 95 °F. (SCS, No. 39 at p. 1) The Joint Utilities Comment stated that DOE should require that all units be certified and rated for SHR at 82 °F ambient db temperature. (Joint Comment, No. 30 at pp. 1, 21) Proctor stated that the rating for humid climates should include information about what portion of the capacity is latent. (Proctor, No. 38 at p. 2)

DOE proposes including the calculation for the SHR within the revised DOE test procedure. (10 CFR part 430, subpart B, appendix M, revised section 3.3c and proposed section 4.5) The Federal Trade Commission (FTC) could then consider incorporating this information in labels for these products.

8. Regional Rating Procedure

DOE received some comments that were supportive and others that were neutral on the development of regional ratings. The Joint Comment noted that DOE already applies regional rating methods in the current test procedure for residential central air conditioners and heat pumps. (Joint Comment, No. 25 at pp. 3-4) It further noted that adoption of regional rating methods might allow DOE to set standards of comparable stringency, but using different rating conditions. (Joint Comment, No. 25 at p. 8) Ice Energy stated that the test protocol should be comprehensive and should span outdoor ambient conditions over the complete range of expected operating conditions. (Ice Energy, No. 33 at p. 3) FSEC stated that DOE should develop new cooling season bin temperature profiles using 2008 typical meteorological year (TMY) data from the National Renewable Energy Laboratory (NREL). (FSEC, No. 31 at pp. 3-4) The National Rural Electric Cooperative Association (NRECA) commented that DOE should evaluate whether its test procedures account for the vast differences in ambient humidity levels in different regions. The air conditioner and heat pump standards should also take into account the effects of humidity on different regional standards. (NRECA, No. 35 at p. 1)

A second Joint Comment (Joint Comment 2) from the National Resources Defense Council, National Consumer Law Center, Inc., and Enterprise stated that DOE should strengthen the SEER test procedure to provide a more robust measure of actual performance in varying conditions in different regions. (Joint Comment 2, No. 36 at p. 2) PG&E noted that DOE needs to reevaluate test procedures to determine the performance of this equipment in the various climate zones. (PG&E, No. 13 at p. 116) EEI suggested

that the test procedure be updated to account for ambient conditions in hot-dry and hot-humid climates. (EEI, No. 20 at p. 3) Proctor commented that the temperature bins used for the rating calculation are not representative of the hotter portions of the United States and provided data representative of specific hot climates. Proctor also commented that the ratings for dry climates should be based only on the sensible capacities measured in the test, and suggested that the sensible capacities and latent capacities, as well as the appropriate watt draws, be measured in the existing 115 °F test. Further, the results of that test should be used in conjunction with any intermediate tests to establish the relationship between the energy efficiency ratio (EER) and outdoor temperature. Proctor also suggested that in defining regions, DOE start with examination of the existing DOE climate map (currently used in the DOE Building Energy Codes Program), which defines dry and humid regions of the United States. (Proctor, No. 38 at pp. 1, 2) SCS also commented that measuring performance at 115 °F would allow the design of temperature bin profiles that better reflect the actual climate of the desert Southwest. SCS supports the concept of a regional rating that reflects actual weather conditions, stating that for a “hot-dry” regional standard, setting the performance rating at 115 °F would be of great value to consumers and would not put an unreasonable burden on manufacturers. (SCS, No. 39 at p. 2) SCS stated, however, that it is neutral at this time on whether a hot-humid regional standard should be established, due to uncertainties about changes in test procedures, future design options manufacturers could use to reach higher efficiency, of the ability of local jurisdictions to limit use of equipment with poor dehumidification performance, and changes in consumer repair versus replacement or substitute behavior due to higher standards. (SCS, No. 39 at pp. 2, 3, 4)

Regarding the comments that favor region-specific cooling mode performance evaluations, DOE proposes changes that will allow the calculation of a region-specific SEER. (10 CFR 430, subpart B, appendix M, proposed section 2.2e and revised sections 3.2.1, 3.2.2.1, 3.2.3, and 3.2.4) The calculation parameters that permit this proposed region-specific SEER are the fractional bin hour distribution and the outdoor design temperature. DOE proposes modifying the indoor wet bulb temperature as part of additional required and optional testing. (10 CFR part 430, subpart B, appendix M, revised sections 3.2.1 (table 3A), 3.2.2.1 (table 4A), and 3.2.2 (table 5A)) These test procedure proposed changes will complement efforts to evaluate the merit of a regional standard for a cooling-dominated region with dry climate. DOE believes that similar changes are not needed for cooling-dominated States with humid climates. The current indoor side entering wet-bulb test condition of 67 °F, fractional bin-hour distribution, and outdoor design temperature sufficiently represent the conditions for a humid climate. Calculation of the SHR from such existing tests, however, is proposed in today's NOPR to quantify the product's dehumidification capabilities.

Section 306(a) of EISA amended section 325(o) of EPCA to require that regions defined for the purposes of regional standards are required to be composed of contiguous States. (42 U.S.C. 6295(o)(6)(C)(i)) In addition, individual States shall be placed only into a single region. (42 U.S.C. 6295(o)(6)(C)(iii)) DOE is proposing an alternative regional efficiency metric, a region-specific SEER (SEER-HD) for a four-State region consisting of Arizona, California, Nevada, and New Mexico. The proposed SEER-HD reflects equipment performance in this region.

DOE does not endorse the recommendation to add testing at 115 °F outdoor temperature. A linear fit of data collected from the cooling mode tests at 82 °F and 95 °F can sufficiently estimate capacity and power consumption at 105 °F, 110 °F, and even 115 °F. Interested parties have not provided, and DOE has not identified, examples where a SEER rating or the proposed region-specific SEER was statistically different as a result of being evaluated based on laboratory data at 115 °F as opposed to 95 °F.

In other related comments, ACEEE asked how DOE would capture and evaluate the efficiency of continuous ventilation for regional standards, as it is provided and used in a reasonable fraction of houses. (ACEEE, No. 13 at p. 138) Sempra indicated that the test protocols should be able to accommodate technologies other than air-cooled expansion unitary equipment. Sempra also commented that DOE should consider using the time value of energy in the new test procedures. (Sempra, No. 13 at p. 121) WCEC contended that certain changes in the test procedures could result in energy savings: (1) A 24-hour test protocol that can measure and characterize the energy and peak demand implications of control and thermal storage technologies; (2) a test protocol that provides different types of evaporative-cooled equipment with directly comparable SEER ratings; and (3) a test protocol that seriously addresses installation and performance-longevity issues. (WCEC, No. 41 at p. 2) ACEEE stated that DOE could use an alternative rating route to deal with enhanced dehumidification products. (ACEEE, No. 13 at p. 154)

Regarding installation and performance longevity issues, DOE does not have the authority to implement new performance metrics for characterizing such features at this time. Presently, the only metrics available for representing performance are SEER and HSPF. These are seasonal performance metrics and are not useful for characterizing installation issues, performance longevity, or quantifying performance at peak demand.

DOE notes that while there may be value in defining a test procedure that can provide consistent, comparable rating of alternative cooling systems, including evaporative cooling technologies and technologies incorporating thermal storage, such expansion of the test procedure is beyond the scope of this rulemaking. This rulemaking seeks to address changes mandated in EISA and otherwise improve upon coverage of comparatively conventional air conditioners and heat pumps. Determining additions and changes needed to allow testing and rating of thermal storage technologies, for example, is a formidable task, one that requires significant investigation. Such an investigation is difficult to pursue until such equipment is readily available as a commercial product.

9. Address Testing Inconsistencies for Ductless Mini- and Multi-Splits

Two interested parties commented that there are inconsistencies within the central air conditioning test procedure for mini- and multi-split systems. (MEUS, No. 13 at p. 21 and 22; Daikin, No. 28 at p. 6)

The proposed changes to items 1 through 3 of Appendix M, cover test procedure changes addressing inconsistencies for ductless mini- and multi-splits. In response to the comments, DOE proposes three changes to the test procedure to address these inconsistencies: (1) Modify the definition of tested combination for multi-split systems. DOE proposes to use the term “nominal cooling capacity” within the definition of “tested combination” (proposed change to 10 CFR 430, subpart A, section 430.2, Definitions, Tested Combination) and to simplify the requirements for multi-split systems with cooling capacities of

24,000 Btu/h or lower; (2) add an alternative minimum static pressure requirement for use when testing ducted multi-split systems (10 CFR 430, subpart B, appendix M, proposed table 2); (3) clarify within the test procedure that optional testing may be conducted without forfeiting the use of default values (10 CFR 430, subpart B, appendix M, proposed section 3.6.4d).

10. Standby Power Consumption and Measurement

Interested parties submitted comments refuting the need to revise the test procedure to consider standby power consumption when EISA does not explicitly call for its revision, and noting that standby power consumption is already addressed in the standard. (AHRI, No. 13 at p. 105; Sempra, No. 13 at p. 133; Energy Solutions, No. 13 at p. 108; Emerson, No. 13 at p. 111) Some contended that the test procedure's accounting of standby power consumption is adequate and does not require modification. (Trane, No. 16 at p. 3; Carrier Corporation (Carrier), No. 18 at p. 1; ASAP, No. 13 at p. 114; MEUS, No. 19 at p. 1; AHRI, No. 24 at p. 2). Trane and Carrier representatives both stated that the standby power consumption calculation is already captured in the degradation coefficient, C
D
calculation. (Trane, No. 16 at p. 3; Carrier, No. 18 at p. 1)

SEER reflects all modes of climate control energy consumption that occur during the cooling season, as HSPF does for the heating season. SEER does not capture the time that an air conditioner could be energized but idle during the non-cooling season. Similarly, the current test procedure does not capture energy consumed by a heat pump during the non-cooling and non-heating seasons. These are the shoulder seasons that occur between the cooling and heating seasons and can be quantified by converting the cooling and heating load hours for any location into actual hours. In each case, the actual site or region-specific cooling and heating season hours always sum to less than 8,760. To calculate annual energy consumption or annual operating cost, all 8,760 hours of the year must be accounted for. Until now, these annual quantities have been based on energy consumption of fewer than 8,760 hours. The DOE test procedure must account for the idle mode energy consumption of the air conditioner and heat pump during the shoulder seasons and the idle mode energy consumption of an air conditioner during the heating season.

Several interested parties commented that although the current standard does address standby power consumption, standby and off mode power need to be better defined. (Joint Comment, No. 25 at p. 6; CFM Equipment Distributors, No. 13 at p. 129; Lennox, No. 13 at pp. 113, 134; Carrier, No. 13 at p. 113; the Unico System, No. 13 at p. 129; Trane, No. 13 at pp. 130, 131, 136; PG&E, No. 13 at pp. 132, 137; General Electric, No. 13 at p. 135; EEI, No. 20 at p. 5; ASAP, No. 13 at p. 132)

DOE concurs with the commenters. The definitions of standby and off mode as provided in EPCA section 325(gg) were amended by section 310 of EISA and are purposely generic so that they can apply to all covered products. (42 U.S.C. 6295(gg)(1)(A)(iii), (42 U.S.C. 6295(gg)(1)(A)(ii), respectively) EPCA section 325 allows DOE to redefine these definitions, including off mode, as part of this rulemaking. (42 U.S.C. 6295(gg)(1)(B)) The proposed definition is as follows:

The term “off mode” means:

(1) For air conditioners, all times during the non-cooling season of an air conditioner. This mode includes the “shoulder seasons” between the cooling and heating seasons when the unit provides no cooling to the building and the entire heating season, when the unit is idle. The air conditioner is assumed to be connected to its main power source at all times during the off mode; and

(2) For heat pumps, all times during the non-cooling and non-heating seasons of a heat pump. This mode includes the “shoulder seasons” between the cooling and heating seasons when the unit provides neither heating nor cooling to the building. The heat pump is assumed to be connected to its main power source at all times during the off mode.

DOE requests comments on this proposed definition (10 CFR, subpart B, appendix M, proposed section 1.48).

B. Summary of the Test Procedure Revisions

Today's proposed rule contains the following proposed changes to the test procedure in 10 CFR part 430, subpart B, appendix M.

1. Modify the Definition of “Tested Combination” for Residential Multi-Split Systems

DOE procedures require testing a complete system, not just its components. For multi-split systems, each model of outdoor unit may be installed with numerous indoor unit combinations. Systems may differ in the number of connected indoor units, their physical type (
e.g.,
wall-mounted versus ceiling cassette, ducted versus non-ducted), and individual capacities.

As part of the October 2007 final rule, multi-split units with rated cooling capacities less than 65,000 Btu/h were newly covered in the DOE central air conditioner and heat pump test procedure. As part of this coverage, manufacturers are required to test each model of a multi-split outdoor unit with at least one set of non-ducted (and at least one set of ducted, if applicable) indoor units. DOE placed limits on the set of indoor units selected to meet this testing requirement for each multi-split outdoor unit. These limits are prescribed in 10 CFR 430.2 definition for “tested combination.” During the previous test procedure rulemaking, DOE refined the “tested combination” definition from the version published in the July 20, 2006 NOPR to the version published in the October 2007 final rule. After implementing the new test procedures, manufacturers of multi-split systems requested additional changes.

In its May 27, 2008 letter to DOE, the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) recommended three changes to the “tested combination” definition. First, AHRI supported changing specific references to “capacity” and “nominal capacity” to “nominal cooling capacity.” AHRI argued that “this correction is necessary to clarify that the test procedures are based on the cooling (rather than heating) capacity of the equipment and to recognize that the nominal means the cooling capacity of the system at 95 °F ambient, 80/67 °F indoor conditions.”

Second, AHRI requested that the requirement preventing the use of an indoor unit having a nominal cooling capacity that exceeds 50 percent of the nominal cooling capacity of the outdoor unit be waived for outdoor units with a nominal cooling capacity of 24,000 Btu/h or lower. AHRI noted that it is not always possible to meet this requirement, especially because of the additional DOE requirement that the nominal cooling capacities of the indoor units, when summed, must fall between 95 and 105 percent of the outdoor unit's nominal capacity. AHRI gave the example of an outdoor unit rated for 20,000 Btu/h that is designed to be used with indoor units having nominal capacities of 9,000 and 12,000 Btu/h. In this case, the only combination that meets the 95 to 105 percent indoor-outdoor capacity criteria is where two indoor units are used, one having a capacity of 12,000 Btu/h and one having a capacity of 9,000 Btu/h. The current definition for tested combination, however, does not allow this combination because the 12,000 Btu/h indoor unit exceeds the 50 percent limit on the capacity of the indoor unit to the capacity of the outdoor unit.

AHRI's final suggested change pertains to multi-split systems with nominal capacities greater than 150,000

Btu/h. The current limit of five indoor units to complete the system is often insufficient for the required 95 to 105 percent match with the outdoor unit. As AHRI stated in its letter, AHRI recognizes that “this capacity is beyond the cooling capacity limit of 65,000 Btu/h * * * but many manufacturers have been granted waivers in which this tested combination definition applies.”

DOE concurs with two of the three changes AHRI requested. DOE proposes to adopt the wording “nominal cooling capacity” within the definition of “tested combination.” (10 CFR 430.2) DOE will also waive the restriction that no indoor unit shall have a nominal cooling capacity exceeding 50 percent of the outdoor unit's nominal cooling capacity for multi-split systems having a nominal cooling capacity of 24,000 Btu/h or less. (10 CFR 430.2(2)(iii)) Additionally, DOE proposes to modify the definition for “tested combination” to indicate that the allowed range for the indoor to outdoor capacity percentages is 95 to 105 percent, inclusive. (10 CFR 430.2(2)(ii) The current wording calls for the match to be “between” (
i.e.,
not “including”) these bounds. Especially with the above switch to using “nominal cooling capacity,” specifying a set of indoor units that yields an indoor to outdoor capacity percentage of either 95 or 105 percent increases should be allowed.

With regard to the third change requested by AHRI, DOE will not establish a different limit on the number of indoor units used when testing multi-split systems with nominal capacities greater than 150,000 Btu/h because these systems are outside the scope of this residential test procedure rulemaking.

2. Add Alternative Minimum External Static Pressure Requirements for Testing Ducted Multi-Split Systems

Since the inception of DOE central air conditioner and heat pump test procedures, the majority of covered products have used a single indoor unit designed to work with a multi-branch duct system to distribute air within a building. This system imposes an additional load (quantified as external static pressure (ESP)) on the indoor blower as it distributes and returns air to and from the conditioned space.

When a system is laboratory tested according to the DOE test procedure, airflow resistance imposed on the blower by external attachments is measured when the indoor blower and the laboratory's airflow measurement apparatus maintain the manufacturer-specified air volume rate. To constitute a valid setup for ducted indoor units, this external resistance measurement must equal or exceed a value—the minimum ESP expressed in wc—specified in the DOE test procedure. The minimum ESP value depends on one of three minimum rated cooling capacities of the tested system: 0.1 in wc for units up to 28,800 Btu/h, 0.15 in wc for units between 29,000 and 42,500 Btu/h, and 0.2 in wc for units 43,000 Btu/h and above. These minimums were adopted from industry standards that were in place when the test procedure was developed and that have remained unchanged.

The majority of multi-split systems use non-ducted indoor units. In laboratory testing following the DOE test procedure, these free discharge units are tested with an ESP of 0 in wc. Multi-splits are also offered where one or more of the indoor units is ducted. Compared with conventional ducted units, indoor unit ducting for multi-splits is shorter and used on the return or supply, or both.

In its May 27, 2008 letter, AHRI stated that “many ductless manufacturers have `ducted' indoor units that are intended for a minimum (less than a few feet) or no duct runs and as a result have a rated external static pressure capability of less than 0.1 ESP and usually around 0.02 ESP.” AHRI recommended a mechanism and language for addressing this issue in the DOE test procedure. Specifically, AHRI suggested that DOE amend its test procedure by adding the following footnote to Table 2 of Appendix M (shown as Table III.1 below): “If the manufacturer's rated external static pressure is less than 0.10 in wc (25 Pascals (Pa)), then the indoor unit should be tested at that rated external static pressure.”

Table III.1—Minimum External Static Pressure for Ducted Systems Tested With an Indoor Fan Installed *

Rated cooling or heating capacity **

Btu/h

Minimum External Resistance
†

in wc

SDHV Systems
††

All other systems

≤ 28,800
1.10
0.10

29,000 to 42,500
1.15
0.15

43,000 ≥
1.20
0.20

* Source: Table 2 from 10 CFR 430, modified for today's NOPR.

** For air conditioners and heat pumps, this is the value the manufacturer cites in published literature for the unit's capacity when operated at the
A
or
A
2
test conditions. For heating-only heat pumps, this is the value the manufacturer cites in published literature for the unit's capacity when operated at the
H1
or
H1
2
test conditions.

†
For ducted units tested without an air filter installed, increase the applicable tabular value by 0.08 in wc.

††
See definition 1.35 to determine if equipment qualifies as an SDHV system. If a closed-loop air-enthalpy test apparatus is used on the indoor side, limit the resistance to airflow on the inlet side of the indoor blower coil to a maximum of 0.1 in wc. Impose the balance of airflow resistance on the outlet side of the indoor blower.

In the field, ducted multi-split systems are installed using lower pressure duct systems than are typically used to install a conventional ducted central air conditioner or heat pump. Consequently, DOE recognizes that ducted multi-split systems should not be subject to the same minimum ESP requirements as conventional central systems. Specifying appropriate minimums, however, is difficult.

One problem with the language AHRI proposed is that a manufacturer could choose an unrealistically low value for the rated external static pressure. Because this would likely be a secondary concern (if not completely overlooked) when a system is selected, the manufacturer lacks an incentive to choose a representative rating. Additionally, because the manufacturer is not allowed to select the minimum external static pressure when testing a conventional unit, allowing the manufacturer to select the minimum when testing a ducted multi-split systems would create an unjustifiable inconsistency.

DOE considered three related factors before formulating an alternative to the AHRI proposal. First, the following approach appears in the Draft International Standard (DIS) ballot of

ISO Standard 15402, “Multi-Split System Air Conditioners and Air-to-Air Heat Pumps: Testing and Rating for Performance.”

This ESP shall be greater than the minimum value given in Table 1 but not greater than 80% of the maximum external static pressure specified by the manufacturer. * * * If the maximum ESP of the unit is lower than the minimum ESP given in Table 1, then the airflow rate is lowered to achieve an ESP equal to 80% of the maximum ESP of the manufacturer. In case this ESP is lower than 25 Pa, the unit can be considered as a free delivery unit.

Where the ISO approach ties the tested minimum external static pressure to a manufacturer published maximum value while approximating the smallest indoor units as non-ducted, the two other inputs suggest that the current test procedure requirements are manageable. Specifically, manufacturers of single indoor blower coil units that use short ducts —sometimes referred to as “furred down or ceiling mounted air handling units”—have never requested that DOE lower the minimum static pressure requirements. Further, DOE has received no evidence showing that any multi-split indoor unit could not achieve the applicable DOE minimum external static pressure when delivering its air volume rate.

DOE proposes an approach that does not require publication of the maximum external static pressure. For the systems meeting the definition of “multiple-split air conditioner and heat pumps” in the test procedure (10 CFR part 430, subpart B, appendix M, section 1.30), DOE proposes a new set of minimum external static pressures. The proposed minimums will be listed in table 2 of appendix M of the test procedure, along with the current values for SDHV and all other systems. The proposed values are 0.03 in wc for units through 28,800 Btu/h, 0.05 in wc for units between 29,000 and 42,500 Btu/h, and 0.07 in wc for units 43,000 Btu/h and above. The proposed minimums seek to capture the relative differences between a conventional central ducted system and one with the shorter ducts of a typical multi-split system installation. Because ducts add resistance, DOE will not adopt the ISO approach of testing the smallest systems at zero static pressure. For multi-split systems, the applicable minimum external static pressure will be assigned based on the nominal/rated cooling capacity of the outdoor unit. A static pressure equal to or higher that this minimum will be achieved in each outlet duct upstream of the point where they connect to the common plenum that leads to the test room's airflow measuring apparatus. In addition to ducted multi-split systems, DOE proposes applying this new set of minimum external static pressures to ducted mini-splits or 1-to-1 systems where the indoor air handler is a ducted furred down/ceiling-mounted unit. To limit the 1-to-1 products that qualify for the lower minimum static pressures, the single indoor unit must not exceed specified dimensions (
e.g.,
no more than 11 in high and less than 24 in deep), the indoor unit must use a single slab coil that is perpendicular to the flow stream, and the system's rated capacity must not exceed 39,000 Btu/h.

DOE requests comment from interested parties on the proposed lower external static pressure levels for certain equipment as described above and on the proposed language for ensuring that these levels are used only for testing the intended products: ducted multi-splits, ducted mini-splits, and ducted furred down/ceiling mounted one-to-one units.

3. Clarify That Optional Tests May Be Conducted Without Forfeiting Use of the Default Value(s)

In the DOE test procedure, the manufacturer has two options for obtaining a required parameter within the SEER or HSPF calculation algorithm: (1) Run one or two additional tests to obtain the necessary data; or (2) use a “default value,” which may be fixed or derived from an approximating equation. For certain frost accumulation tests, the DOE test procedure gives the manufacturer the option of conducting the test or using default equations to determine the pump's power consumption and space heating capacity at 35 °F outdoor temperature and at the designated compressor capacity. The test procedure is not clear whether defaults are forfeited if the manufacturer conducts the optional laboratory test. This matter is clarified here.

As stated in the DOE test procedure (10 CFR part 430, subpart B, appendix M, sections 3.2.1, 3.2.2.1, and 3.2.3), the manufacturer may run the optional test(s) for determining a cyclic degradation coefficient but still use the default if it is lower than the tested value. DOE proposes allowing manufacturers to run the optional test(s), with the understanding that they can still use the default value if it is more favorable for optional frost accumulation tests. Specifically, the manufacturer may use the power consumption and heating capacity values derived from conducting the optional frost accumulation test or the values calculated using the default equations, whichever set contributes to a higher Region IV HSPF based on the minimum design heating requirement.

4. Allow a Wider Tolerance on Air Volume Rate To Yield More Repeatable Laboratory Setups

A goal of the DOE test procedure is specifying a consistent equipment configuration to obtain repeatable laboratory test results. For example, the indoor blower of a particular model should be consistently set to the same blower speed setting for a given test configuration. More generally, the blower speed setting should be the same when performing the same test on all units of the same equipment model.

As part of the equipment setup requirements for most blower-coil units, the testing entity (
e.g.,
manufacturer or third party) turns on both the indoor unit blower and the test facility exhaust fan. The exhaust fan and/or an airflow damper are adjusted until the manufacturer-specified indoor air volume rate is obtained. If the measured external static pressure equals or exceeds the test procedure specified minimum value, testing proceeds without adjustment to the indoor unit configuration.

If the measured external static pressure is below the DOE minimum, the setup requires additional effort. The first step is to reduce the air volume rate until the measured external static pressure equals the DOE minimum. As currently specified in the test procedure, if the measured external static pressure does not equal the DOE minimum by the time the air volume rate has been reduced to 95 percent of the rated value, then the indoor unit blower is turned off, and the indoor unit's setup is adjusted to the next highest speed setting.

The above setup procedure will typically result in the indoor blower-coil set to the same speed setting for testing all units of the same model. In essence, the procedure handles the inherent variability in the external static pressure and air volume rate produced and measured for multiple equipment setups. This variability is due to manufacturing tolerances and lab measurement uncertainties.

In its May 27, 2008 letter, AHRI requested that the 5-percent tolerance on air volume rate be increased to 10 percent. In addition, AHRI recommended that the language for the indoor blower coil setup procedure be refined to recognize that some incremental setting changes may affect more than fan speed. AHRI gives the example that “some speed tap settings may equate to a specific duration of fan delay whereas other settings may translate to no fan delay.” To address this issue, AHRI recommends that DOE

make incremental changes to the indoor blower setting among settings that provide similar operating features.

AHRI offers two reasons in its May 27, 2008 letter for supporting a greater tolerance on air volume rate during the initial setup process: The expanding use of constant torque motors for central air conditioners and heat pumps blower coils, and the effect of barometric pressure. AHRI states that “for a given speed tap, the air volume rate achieved using a constant torque motor is comparatively more variable; also the change in power draw as a function of an incremental change in the speed tap is also comparatively greater so the impact on efficiency will be more pronounced.” Barometric pressure affects air density and the water vapor content for a given db/wb combination. Thus, barometric pressure affects capacity through both the air volume rate and the enthalpy change of the air. As referenced in the AHRI letter, barometric pressure effects are especially important, as most manufacturers' in-house testing is conducted at a lower elevation and typically higher barometric pressure than at the industry's primary independent certification testing facility.

In response to AHRI's May 27, 2008 letter, DOE proposes to increase the tolerance on air volume rate from 5 to 10 percent. In addition, DOE proposes to adopt AHRI's recommendation to refine the indoor blower coil setup procedure to recognize that some incremental changes to the setting may affect more than the fan speed. DOE used computer modeling and laboratory data to determine that a 10 percent difference in air volume rate will cause total capacity to decrease between 1.3 to 2 percent, while having the total system power consumption fall between 1 to 1.8 percent for a minimally compliant system. Because capacity and power impacts are similar, the EER and SEER impacts are less. SEER is projected to decrease between 0.2 and 0.4 percent. Thus, this proposed change has the potential to affect the measured capacity such that it may make it more difficult to meet the industry certification program's 95 percent capacity tolerance. The impact on the DOE regulated descriptor of SEER, however, is well within the measurement uncertainty, even for the limiting case of a 10-percent departure.

DOE requests data and comments from interested parties on the impact of the change from 5 to 10 percent tolerance on air volume rate.

5. Change the Magnitude of the Test Operating Tolerance Specified for the External Resistance to Airflow and the Nozzle Pressure Drop

The DOE test procedure specifies both test operating and condition tolerances. Test operating tolerances indicate the maximum range that a parameter may vary during the data collection interval. For any given test, operating tolerances are specified for a few different parameters. For each parameter, the difference between the highest and lowest instantaneous measurement for the data collection interval must not exceed the specified operating tolerance in order to constitute a valid test.

The test operating tolerance for external resistance to airflow is 0.05 in wc. The test operating tolerance for nozzle pressure drop is 2.0 percent. Both tolerances, which apply for all cooling and heating tests were included in industry standards (
e.g.,
ASHRAE Standard 37) that pre-date the first publication of the DOE central air conditioner and heat pump test procedure. The DOE test procedure adopted the two tolerances at its inception and has not changed it. For current industry standards, the tolerances appear in the 2009 version of ASHRAE Standard 37.

The two test operating tolerances are often exceeded when an electronic pressure transducer is used to measure differential pressure instantaneously. The likelihood of exceeding the tolerance increases with higher sampling rates and when testing indoor blowers whose controls actively regulate operation of the blower's motor. One example is a blower with a variable-speed motor designed to maintain the air volume rate regardless of the airflow resistance. In contrast, these test operating tolerances are usually satisfied if the differential pressures are measured using liquid manometers. The fluid provides mechanical damping that tends to stabilize readings.

DOE proposes to loosen the existing tolerances from 0.05 to 0.12 in wc for the test operating tolerance assigned to the external resistance to airflow and from 2.0 percent to 8.0 percent for the nozzle pressure drop tolerance because the pressure fluctuations are real (10 CFR, subpart B, appendix M, revised tables 7, 8, 13, 14 and 15). The proposed changes in the magnitude of the tolerances are based on limited data obtained from laboratory testing of a variable-speed, constant air-volume-rate blower using electronic pressure transducers with a 5-second sampling rate. This data indicated that the current tolerances could rarely be achieved when using and electronic pressure transducer instead of a liquid manometer. Matching or remaining within the proposed tolerances, by comparison, was far more achievable.

At this stage, DOE proposes amended values for the two tolerances rather than their complete elimination because they still help assure data is taken during a period of relatively steady operation. Additional steps, however, may be warranted. For example, a prescribed algorithm for identifying outliers and/or establishing minimum intervals over which all instantaneous measurements are averaged (
e.g.,
minutely averages) may also be needed to strike the necessary balance between defining test tolerances that promote repeatable test results while not extending test times. Another option may be to introduce a mechanical means for damping the high frequency pressure fluctuations that are fed to the electronic pressure transducer to mimic a liquid manometer. Such damping would be acceptable because the measurements would still reveal whether the flow was steady or trending higher or lower.

DOE seeks comments from interested parties about the proposal to increase the test operating tolerance for the external resistance to airflow from 0.05 to 0.12 in wc and increase the test operating tolerance for the nozzle pressure drop from 2.0 percent to 8.0 percent. In addition, comments on alternative or additional steps to assure the capacity and electrical power data are collected over a 30-minute period of consistent operation are encouraged.

6. Modify Third-Party Testing Requirements When Charging the Test Unit

DOE proposes to revise section 2.2.5, “Additional refrigerant charging requirements,” of the test procedure. Most of the proposed revisions originate from the requirements listed in section 9.8.1.1 of the 2008 ARI General Operations Manual for AHRI Certification Programs. DOE adopted the current language in section 2.2.5 of the DOE test procedure in the October 2005 final rule. The section 2.2.5 text covers details not addressed in the test procedure prior to the October 2005 rule, such as charging instructions that differ for field installations versus laboratory testing and the procedure for manufacturers and third-party testing entities to resolve questions on charging a particular system. In the months following publication of that rule, AHRI members reconsidered refrigerant charging, mainly within the context of implementing its third-party certification program. During the August

23, 2006 public meeting, Rheem Manufacturing Company shared AHRI's view of key shortcomings. These include provisions in section 2.2.5 regarding available options when a unit is charged and tested by a third party. These provisions failed to disallow charge manipulation during the testing process (
e.g.,
different charging criteria for the cooling mode tests versus the heating mode tests).

AHRI provided language from the current version of the AHRI General Operations Manual so that all or part of it may be considered for incorporation into the DOE test procedure. The specific AHRI text of interest is as follows:

9.8.1.1
Test Sample Refrigerant Charge.
All test samples will be charged in accordance with the following instructions and those provided in the manufacturers' Installation and Operational (I/O) Manuals.

Determine refrigerant charge at the Standard Rating Condition in accordance with instructions from I/O Manual. For a given specified range for superheat, sub-cooling, or refrigerant pressure, the average of the range shall be used to determine the refrigerant charge. If multiple instructions are given, the manufacturer will be asked to sign off on the preferred method.

The testing laboratory will then add or subtract the correct amount of refrigerant to achieve the pre-determined superheat, sub-cooling, or refrigerant pressure. This single charge will then be used to conduct all cooling cycle and heating cycle tests.

Once the correct refrigerant charge is determined, the test will run until completion without interruption.

DOE proposes to adopt selected elements of the above AHRI procedures. (10 CFR part 430, subpart B, appendix M, section 2.2.5) The proposed changes promote consistency with current AHRI certification practices, including explicitly disallowing charge manipulation once the initial charging procedure is completed, while differing on the approach of addressing cases where a manufacturer either provides no instructions or provides more than one set of charging instructions. In particular, DOE chose not to implement a “sign off” option as AHRI uses because the proposed approach of specifically addressing the setup procedure in these two special cases is effective and less burdensome.

7. Clarify Unit Testing Installation Instruction and Address Manufacturer and Third-Party Testing Laboratory Interactions

DOE proposes to add language to section 2.2 of the test procedure. The additions seek to clarify installation instructions and, when third-party testing is conducted, to clarify that interaction with the manufacturer is allowed.

The AHRI Certification Program and the DOE test procedure focus on different aspects of the rating process. The AHRI program conducts verification testing of full production of randomly sampled units taken from the manufacturer's inventory. By comparison, the DOE test procedure is typically conducted before a new model of air conditioner or heat pump is introduced into the market. Therefore, testing is usually performed on first production or pre-production units, each of which meets the requirement in 10 CFR 430.24 that testing be done on “units which are production units, or are representative of production units.” When testing pre-production units, the installation instructions are not packaged with the unit or perhaps not even finalized. DOE proposes adding language on how to handle such cases. (appendix M, revised section 2.2) Some of the restrictions on interactions between third-party testing laboratories and manufacturers, imposed as part of the AHRI Certification Program, do not apply to the DOE test procedure. One example is AHRI's General Operations Manual requirement that “only laboratory personnel shall install test units.” The policy is useful to AHRI because certification testing checks DOE ratings. AHRI does not want individual manufacturers to slow the testing process or reveal information about a competitor. On the other hand, DOE will not prohibit a manufacturer from interacting with a third-party testing laboratory if the latter is contracted to perform work similar to in-house manufacturers. (10 CFR part 430, subpart B, appendix M, revised section 2.2a) In the event of a DOE enforcement action, DOE places no restrictions on manufacturer involvement as long as the test unit installation and laboratory testing are conducted in complete compliance with all other requirements in the DOE test procedure. The highest order of these other requirements is to install the unit according “the manufacturer's installation instructions,” as stated in section 8.2 of ASHRAE Standard 37, where the first source for those instructions is the published literature that comes packaged with the unit.

This second issue on the allowed interactions between third-party testing laboratory and the manufacturer was addressed in a previous rulemaking (70 FR 59122) but only as it pertained to the specific installation step of refrigerant charging (section 2.2.5 of the test procedure). Because the interaction applies to the entire installation process, DOE proposes to address the issue in section 2.2 and, as a result, existing section 2.2.5 language on this topic is proposed for deletion.

8. When Determining the Cyclic Degradation Coefficient C
D
, Correct the Indoor-Side Temperature Sensors Used During the Cyclic Test to Align With the Temperature Sensors Used During the Companion Steady-State Test, If Applicable

In the DOE test procedure, the results from two optional dry-coil cooling mode tests—one steady-state, one cyclic—provide the inputs to calculate cooling mode cyclic degradation coefficient(s),
C
c
D
. For the heating mode, the results from one of the required steady-state tests plus the results from an optional cyclic test are used to calculate the heating mode cyclic degradation coefficient,
C
h
D
. In all cases, the two tests for calculating a cyclic degradation coefficient are conducted consecutively, with the steady-state test conducted first.

Both the steady-state (10 CFR part 430, subpart B, appendix M, sections 3.4 and 3.7) and cyclic (10 CFR part 430, subpart B, appendix M, sections 3.5 and 3.8)
C
D
tests require calculating the change in the db temperature on the indoor side. To complete these measurements, the laboratory test setup includes redundant sets of temperature sensors and associated instrumentation. In many cases, one set of temperature sensors provides the primary measurement of the change in db temperature for all steady-state tests, while the second set provides the same primary measurement for all transient tests, including the cyclic
C
D
test. Using two sets of temperature sensors allows highly accurate measurements during the steady-state test; comparatively less accurate but necessarily faster-responding measurements are achieved during the transient tests. The DOE test procedure refers to ASHRAE Standard 41.1-1986 (RA 2001) for recommendations and requirements on making these temperature measurements.

Cyclic degradation coefficients are used to obtain a relationship between part-load factor (PLF) and the percent on-time of the unit. PLF is a ratio of the cyclic to the steady-state EER. The consecutive
C
D
tests are used to obtain one point on the PLF versus percent on-time plot. Because the results of the consecutive
C
D
tests define a ratio, the preferred testing approach is to limit differences between the two tests. Using one set of instrumentation to measure the change in the db air temperature entering and leaving the indoor unit

during the steady-state
C
D
test and a different set for the companion cyclic
C
D
test is a source of potential bias.

To avoid conflict, DOE may require that the same temperature measurement instrumentation be used for both consecutive
C
D
tests. The Standards Project Committee revising ASHRAE Standard 116, “Methods of Testing for Rating Seasonal Efficiency of Unitary Air Conditioners and Heat Pumps,” considered this alternative but chose to make it a recommendation, not a requirement (see clause 5.1.4 of ASHRAE Standard 116-1995R, “Method of Testing for Rating Seasonal Efficiency of Unitary Air Conditioners and Heat Pumps,” First Public Review draft). A second option is to correlate the instrumentation used for the primary measurement of the temperature difference of the cyclic
C
D
test to that used for the primary measurement during the steady-state
C
D
test. Some industry members have implemented this correlation approach and found that it improves repeatability.

DOE proposes to require a correlation step for testing laboratories that use different instrumentation to measure the change in the db temperature of the air entering and leaving the indoor unit during the steady-state
C
D
test versus the cyclic
C
D
test. This correlation step is conducted during the steady-state
C
D
test. During the test, both sets of instrumentation—those sensors providing the primary measurement during the steady-state (set SS) and during the cyclic (set CYC) tests—measure the indoor-side air db temperature difference. For both sets of instrumentation, measurements made at equal intervals that span 5 minutes or less determine the temperature difference. Once the 30-minute data collection period begins for the steady-state
C
D
test, an average temperature difference is calculated based on the sets SS and CYC instrumentation after a minimum of 7 data samples and 6 minutes or more. The average temperature differences are then used to calculate the
C
D
correlation factor,
F
CD
:

EP02JN10.304

An updated
F
CD
value shall be recalculated every minute or after each data sample, whichever occurs later. In addition, each recalculated ratio shall be based on the same number of data samples and same elapsed time as used for the first
F
CD
. For the example case of a sampling rate of 1 minute or less, the first
F
CD
shall be based on data collected from elapsed time of 0 to 6 minutes, the second from 1 to 7 minutes, the third from 2 to 8 minutes, and so on.

Upper and lower limits are proposed for
F
CD
to provide a uniform basis as to how much the two temperature measurements may deviate. The proposed allowable range of
F
CD
is 0.94 to 1.06. Laboratories that sample at a rate of every minute or less can evaluate the first
F
CD
as soon as 6 minutes after the start of the normal 30-minute data collection period. If this first or any subsequent value of
F
CD
is outside the proposed application range of 0.94 to 1.06, then the testing laboratory can make a decision to abort the test in advance of completing the 30-minute data collection period. By comparison, if a 5-minute sample rate is used,
F
CD
falling within the allowed range will remain unknown until the 30-minute data collection period is completed. In this case, up to 24 minutes of laboratory testing time may be lost from a longer wait to evaluate compliance.

If the value of
F
CD
at the conclusion of the 30-minute period (saved
F
CD
) falls outside the range of 1.0 ± 0.6, then the test sequence must be terminated, and steps taken to improve the agreement between the sets SS and CYC instrumentation. Calibration of one or both sets of instrumentation in accordance with ASHRAE Standard 41.1 may be necessary. Once the remedial steps are complete, the steady-state
C
D
test shall be repeated. For cases within the accepted range, the saved
F
CD
shall thereafter be used during the cyclic
C
D
test to adjust the indoor-side temperature difference or a time-integrated value of the same determined using the set CYC instrumentation. For example, with respect to section 3.5 of Appendix M, the equation for the integrated, indoor-side air temperature difference will be written as follows:

EP02JN10.303

The value of
F
CD
shall be used only to adjust the set CYC temperature difference measurement from the cyclic
C
D
test that immediately follows the steady-state
C
D
test that yields the correlation factor. The
F
CD
determined and applied for one set of consecutive
C
D
tests shall not be used to adjust the set CYC temperature difference measured during a second cyclic
C
D
test or during a frost accumulation test.

DOE proposes to decrease the minimum sampling rate of the db temperature difference from the current value of every 10 minutes to every 5 minutes to obtain a more representative value of
F
CD
. As an extension of this modification, DOE proposes to change the long-standing minimum sampling rate for all steady-state tests from 10 to 5 minutes. The 10-minute sampling interval rate allows time for some measurements to be hand-recorded. Improved test quality and results, advances in electronic instrumentation, and the low cost of computer-based versus manual recording justify the minimum sampling rate change.

DOE seeks comments from interested parties on the introduction and calculation of the cyclic degradation correlation factor. DOE also seeks comments on the change in sampling rate from 10 to 5 minutes.

9. Clarify Inputs for the Demand Defrost Credit Equation

The demand defrost credit (
F
def
) is a direct multiplier within the HSPF calculation Eq. 4.2-1 in the DOE test procedure. The factor provides nominal credit for heat pumps with a demand defrost control system. Systems that meet DOE requirements in test procedure definition 1.21, “demand defrost control system,” qualify for this credit. The multiplier has a value between 1.00 and 1.03, which is a 0 to 3 percent increase in the HSPF rating. The credit is evaluated using the following equation from section 3.9.2 of the DOE test procedure:

EP02JN10.239

Where:

Δτ
def
= time between defrost terminations (in hours) or 1.5, whichever is greater, and

Δτ
max
= maximum time between defrosts as allowed by the controls (in hours) or 12, whichever is less.

The demand defrost credit was incorporated into the test procedure during the rulemaking completed in March 1988 and has remained unchanged. 53 FR 8319. DOE mistakenly overlooked inputs to this equation during the most recent test procedure final rulemaking, in which DOE shortened the maximum duration of all frost accumulation tests from 12 to 6 hours. DOE has since considered two options for calculating the credit: (1) Update the evaluation of
Δτ
max
to read “maximum time between defrosts as allowed by the controls (in hours) or 6 hours, whichever is less;” and (2) reinforce that the current form of the equation still applies and, when a defrost cycle is not completed before the maximum time, assign
Δτ
def
the value of 6 hours. DOE proposes to adopt this second option in today's notice.

As discussed in the October 2007 final rule, the change from a maximum

test duration of 12 to 6 hours rarely affected testing; when it did, there was a negligible impact on the calculation of the average heating capacity and power consumption at a 35 °F outdoor temperature. The main reason for changing the maximum limit to 6 hours was to reduce the test burden when frost did not build on the outdoor coil. The frost accumulation tests at low-capacity for two-capacity heat pumps and at the intermediate compressor speed for variable-speed units are the two leading cases where this revision may help reduce that burden. Since the institution of this change, DOE has not received any comments or information about the effects on heating capacity or power.

Shortening the maximum duration of the frost accumulation test affects heat pumps that would otherwise conduct a defrost after 6 but before 12 hours in two ways. First, as recognized during the October 2007 final rule process, such heat pumps benefit slightly from not having a defrost cycle factored into their average heating capacity calculation. Second, they earn a higher demand defrost credit than they would have earned previously. As a worst case (
e.g.,
unit's demand defrost controls actuate at 11.999 hours while the unit's maximum duration is 12 hours or more), the approximated demand defrost credit is now 1.017 compared to the “true” value of 1.000.

In summary, the proposed rule includes additional language clarifying that manufacturers must assign
Δτ
def
the value of 6 hours if this limit is reached during a frost accumulation test and the heat pump has not completed a defrost cycle. A sentence is also added to indicate that the manufacturer must provide the value of
Δτ
max
.

DOE seeks comments from interested parties on this proposal for calculating the demand defrost credit (
F
def
) for cases where the Frost Accumulation Test is terminated because the heat pump does not initiate a defrost within the maximum allowed 6-hour heating interval.

10. Add Calculations for Sensible Heat Ratio

SHR is a parameter that indicates the relative contributions of the air conditioner's or heat pump's cooling output that reduces the db temperature of the air (
i.e.,
sensible cooling) to the cooling output that reduces the moisture content in the air (
i.e.,
latent cooling). The parameter is calculated by dividing the sensible cooling capacity by the total cooling capacity. Total cooling capacity is the sum of the sensible and latent cooling capacities. For example, an SHR of 0.75 indicates that 75 percent of the cooling is sensible and 25 percent is latent.

The DOE test procedure considers total building cooling loads and total cooling equipment capacities as part of the SEER calculation. The cooling load and capacity are not divided into their sensible and latent components. Based on historical data, equipment SHRs have remained relatively unchanged as equipment SEER ratings have increased. In addition, cooling equipment has historically provided a reasonable match to the sensible and latent loads of the building or residence. However, better insulation of homes and small commercial buildings has helped reduce sensible building loads. Particularly in more humid climates, this reduction in the sensible building load can make the latent building load more prominent.

SHR differences among equipment having approximately the same SEER have always existed. For example, 2001 Amrane, Hourahan, and Potts data reported in the January 2003
ASHRAE Journal
(pp. 28-31) show SHR values that vary by at least 0.10 for a given SEER value. When humidity control is a concern, consumers and their contractors may wish to know the SHRs of different units to make a more informed decision.

The measurements required to calculate the SHR from a DOE wet-coil cooling mode test are taken as part of the DOE test procedure. In fact, manufacturers and independent testing laboratories routinely determine SHR. DOE proposes to add the SHR calculation to its test procedure to endorse the calculation and its continued use explicitly. (10 CFR part 430, subpart B, appendix M, revised section 3.3c and proposed section 4.5)

11. Incorporate Changes to Cover Testing and Rating of Ducted Systems Having More Than One Indoor Blower

The majority of residential central air conditioners and heat pumps employ a single blower and a single refrigerant-to-air coil. Typical multi- and some mini-splits use more than one indoor unit, with the indoor units using one blower and one coil. However, a newer type of residential central system that uses more indoor blowers than indoor coils does not follow this one-to-one blower-to-coil ratio.

The multi-blower design facilitates zoning when the system responds to more than one thermostat. Associated with the zoning feature are capacity modulation and variations in electrical power consumption. The first and more limited means of affecting capacity and power use is controlling the number of indoor blowers that are turned on and, where applicable, altering the blower's speed (if equipped with a multi-stage or variable-speed motor). The second and broader means of affecting power consumption occurs in systems that use a single outdoor unit equipped with a two-stage compressor or in systems consisting of two outdoor units, each having single-speed compressors.

DOE proposes modifications to cover the testing and rating of systems using a multi-blower indoor unit. These systems will be treated as if all zones depend on outdoor temperature such that they respond to the same load profile as a single-zone system. DOE test procedure algorithms for covering two-capacity units and systems having a single-speed compressor with a variable-air-volume rate indoor blower would provide the basis for the algorithms that address systems with a multi-blower indoor unit (10 CFR 430, subpart B, appendix M, revised sections 2.2.3, 2.4.1, 3.1.4.1.1, 3.1.4.2, 3.1.4.4.2, 3.1.4.5, 3.2.2, 3.2.2.1, and 3.6.2; proposed sections 3.2.6, 3.6.7, 4.1.5, and 4.2.7; and revised tables 4 and 10).

On August 28, 2008, DOE published a decision and order granting a waiver from the DOE Residential Central Air Conditioner and Heat Pump Test Procedure for a line of multi-blower indoor units that may be combined with one single-speed heat pump outdoor unit, one two-capacity heat pump outdoor unit, or two separate single-speed heat pump outdoor units. 73 FR 50787-50797. For the two separate single-speed outdoor units, the chosen indoor coil contains two independent refrigeration circuits, each fed by one of the outdoor units.

The above-referenced waiver covers products that use two to eight indoor blowers with a single- or dual-circuit indoor coil. To simplify the testing and rating algorithm, DOE structured the waiver so that each system was evaluated with all and with half of the indoor blowers operating. DOE did not consider any other potential blower combinations. For systems offering compressor modulation, a high-stage compressor operation was evaluated only when all blowers were on, and the low-stage was evaluated with half the blowers on.

DOE proposes to amend the test procedure to allow the coverage of systems that use a multi-blower indoor unit to address the same type of equipment covered by the test procedure waiver granted to Cascade Group, LLC.

12. Add Changes To Cover Triple-Capacity, Northern Heat Pumps

On February 5, 2010, DOE granted Hallowell International a waiver from the DOE test procedure on how to test and rate its line of boosted compression heat pumps. (24 FR 6014-6018) These heat pumps offer three stages of compressor capacity when heating, with the third stage being designed to provide greater heating capacity at the lowest outdoor temperatures. The approved waiver contained additional laboratory tests and calculations steps that were specific to obtaining an HSPF rating for the Hallowell heat pumps. No changes to the DOE test procedure were required to evaluate the SEER for these heat pumps. The test procedure sections covering two-capacity systems when operating in a cooling mode are applicable for the Hallowell heat pumps.

Proposed test procedure amendments are offered as part of this rulemaking to cover heat pumps that provide three levels or stages of heating capacity like the Hallowell units. The proposals seek to cover the more generic case of such technology.. The proposal includes, additional laboratory testing to capture the effect on both capacity and power of the additional stage of heating operations.. The proposed building load assigned by HSPF calculations requires evaluation based on the application in which high-stage compressor capacity for heating exceeds that for cooling. Finally, the proposed coverage accounts for controls that lock out one or two heating mode capacity levels at any given outdoor temperature. Once these proposals are incorporated into the test procedure, the need for a waiver will be eliminated and the requirements will apply to all manufacturers who offer equipment with this technology.

DOE proposes adding two required steady-state tests to quantify the heating capacity and power consumption characteristics of the third stage of heating. One test would be conducted at the existing outdoor temperature test condition of 17 °F db/15 °F wb temperature (
H3
3
). The second test would be at a new outdoor test condition (
H4
3
), 2 °F db/1 °F wb. This proposed outdoor temperature condition is slightly higher than the 0 °F db/−2 °F wb condition proposed by Hallowell and cited in the approved waiver. The alternative condition is proposed with the intent of specifying a test condition that is marginally more achievable for testing laboratories. Finally, two optional tests are proposed, a Frost Accumulation Test and a cyclic test with the heat pump operating at its third or boosted compression stage (10 CFR part 430, subpart B, appendix M, proposed section 3.6.6).

DOE is proposing equations for calculating the capacity and electrical power consumption of the heat pump as a function of the outdoor temperature when operating at its highest stage of compressor capacity. As part of the proposal, the heating building load used in the HSPF calculation, would also be based on the capacity measured during the
H1
test condition (47 °F db/43 °F wb outdoor temperatures). The compressor would operate at the same speed or stage as in the (
A
2
) cooling mode test at 95 °F outdoor db. The HSPF calculation algorithm would be an extension of the approach currently used in the DOE test procedure for two-capacity heat pumps. The active stages of heating capacity available for each bin temperature calculation would be based on the control logic of the unit (10 CFR part 430, subpart B, appendix M, proposed section 4.2.6).

DOE seeks comments from interested parties on the inclusion of test procedure amendments to cover heat pumps that offer three stages of compressor capacity when heating.

13. Specify Requirements for the Low-Voltage Transformer Used when Testing Coil-Only Air Conditioners and Heat Pumps and Require Metering of All Sources of Energy Consumption During All Tests

The transformer that powers the low-voltage components of a field-installed hot-air furnace and add-on (coil-only) air conditioner or heat pump resides in the furnace. A coil-only air conditioner or heat pump with a hot-air furnace is not typically laboratory tested. As a result, the DOE test procedure does not specify the low-voltage source of power for the compressor contactor, control boards, and most heat pump reversing valves. Because the test procedure does not stipulate metering requirements, the associated power consumption is typically unmetered, which makes the choice of the transformer used inconsequential. A 100 volt amp (VA) transformer powered by a 230 V input works as well as a 40 VA model powered by a 115 V input.

Because coil-only equipment mainly competes against like equipment, not accounting for low-voltage components' power consumption in the past was not a glaring deficiency as the comparable impact on SEER and HSPF ratings. However, in seeking to account for all modes and sources of energy consumption as per section 310 of EISA 2007, DOE proposes that the energy consumption of low-voltage components of coil-only systems be measured and included in the applicable rating descriptors. DOE anticipates needing to specify a VA rating for the transformer used for laboratory testing, while requiring that the input voltage be the same as that provided to the outdoor unit (
e.g.,
230 V).

An indoor wall thermostat is not typically used for laboratory testing of a central air conditioner or heat pump. For this rulemaking, DOE considered but decided against assigning a default power value to account for the absence of the wall thermostat. Some thermostats use no power or are battery powered. If a low-voltage-powered electronic thermostat is used, its power consumption is often low, usually less than a watt or two. In most cases, an air conditioner or heat pump can be installed in a system that includes a variety of wall thermostats. It is not possible to know the type of thermostat that will be used or its power consumption.

For testing coil-only air conditioners and heat pumps, DOE proposes that the power consumption of the low-voltage system components be metered. Additionally, the transformer would be rated to provide 24 V, have a load rating of either 40 or 50 VA, and would be designed to operate with a primary input of 230 V, single phase, 60 hertz. The transformer may be powered by the same source as the outdoor unit or a separate 230 V source. The key requirement is that the instrument measuring the transformer's power consumption during the off mode power or any other test must do so within the prescribed measurement accuracy.

14. Add Testing Procedures and Calculations for Off Mode Energy Consumption

SEER is a seasonal descriptor that accounts for all (modes of) energy consumption that occurs during the cooling season, including times when the air conditioner or heat pump is cycled off because the building thermostat is satisfied. HSPF is a seasonal descriptor for heat pumps that accounts for all (modes of) energy consumption during the heating season. The current test procedure does not cover the energy consumption of an air conditioner during the heating season when the unit is typically turned off at the thermostat but its controls and protective devices remain energized. The current test procedure also does not account for a complete 8,760-hour year as part of the annual cost calculation. As documented in appendix A of ASHRAE Standard 137-2009, “Method of Testing

for Efficiency of Space-Conditioning/Water Heating Appliances that Include a Desuperheater Water Heater,” the combination of the location-specific cooling and heating load hours used in the annual cost calculation is less than 8,760. The missing hours correspond to the intervals during which space conditioning is not required because the outdoor temperature is moderate, as during the shoulder seasons that occur between the cooling and heating seasons. Neither SEER nor HSPF account for energy consumed during the shoulder seasons.

To provide a means for more clearly accounting for the energy consumption during the shoulder seasons and, for air conditioners, the energy consumption during the heating season, DOE proposes to define that such times occur when the air conditioner or heat pump is in an “off mode.” DOE proposes the following definition.

The term “off mode” means:

(1) For air conditioners, all times during the non-cooling season of an air conditioner. This mode includes the “shoulder seasons” between the cooling and heating seasons when the unit provides neither heating nor cooling to the building plus the entire heating season, when the unit is idle. The air conditioner is assumed to remain connected to its main power source at all times during the off mode; and

(2) For heat pumps, all times during the non-cooling and non-heating seasons of a heat pump. This mode includes the “shoulder seasons” between the cooling and heating seasons when the unit provides neither heating nor cooling to the building. The heat pump is assumed to remain connected to its main power source at all times during the off mode.

Notably, the above proposed definition differs from the one provided in section 310 of EISA 2007, which amended section 325(gg)(1)(A) of EPCA. (42 U.S.C. 6295(gg)(1)(A)) This section of EPCA applies to a wide range of covered products, and as a result, the definitions for off-mode, active mode, and standby mode are relatively general in order to address all possible energy consuming modes. Rather than introduce alternative definitions for all of these modes within the central air conditioner and heat pump test procedure, DOE proposes modifying only the definition for off-mode as part of this rulemaking.

DOE proposes new laboratory tests and a separate calculation algorithm for estimating the energy consumption during the off-mode season. The new tests and calculations are used to determine an average power consumption for the collective shoulder seasons and, for air conditioners, an average power consumption during the heating season. The shoulder season's off-mode power consumption will be designated as
P1,
which affects both air conditioner and heat pump energy usage. The heating season off-mode power consumption will be designated as
P2,
which only affects air conditioner energy usage.

(10 CFR part 430, subpart B, appendix M, proposed section 3.13)

DOE has determined that it is not technically feasible to integrate off-mode energy use into the SEER and HSPF metrics because they are both seasonal descriptors. These seasonal descriptors should not be used to account for the out-of-season of off-mode energy consumption—i.e., the energy consumed during the shoulder seasons and during the heating season. To do so would alter the basis of SEER and HSPF. The basis for the integrated SEER for an air conditioner would be annual performance, while the basis for the integrated SEER and HSPF for a heat pump would be part-year performance. Annual and part-year bases for SEER and HSPF are inconsistent with the definitions of these regulating metrics. Moreover, the difference in bases, annual for the air conditioner versus part-year for the heat pump, disallows the use of the integrated SEER for comparing an air conditioner to a heat pump. Therefore, to maintain the technical integrity of SEER and HSPF and to account for off-mode (off season) energy consumption, DOE has developed a separate algorithm to calculate the off-mode (off season) energy consumption.

The proposed
P1
and
P2
parameters are used to evaluate the off-mode energy consumption for any generalized climatic region or specific location.

The shoulder season average off-mode power
P1
(for air conditioners and heat pumps) would be multiplied by the appropriate shoulder season hours to obtain the energy consumed during the collective shoulder seasons. For air conditioners during the heating season, the average off-mode power
P2
would be multiplied by the applicable heating season hours to obtain the energy consumed. The calculation of an air conditioner's annual energy consumption and annual operating cost would include both the shoulder season energy consumption and the energy consumed during the heating season. For heat pumps, the energy consumption during the shoulder seasons would be included in the calculation of the annual energy consumption and annual operating cost.

As part of today's notice, DOE provides the actual hours associated with cooling, heating, and the collective shoulder seasons for six generalized climatic regions currently defined in the test procedure. DOE also includes actual hours that correspond to the 1,000 cooling load and the 2,080 heating load hours referenced in 10 CFR 430.23(m), “Test procedures for the measurement of energy and water consumption—central air conditioners and heat pumps,” as the representative average use cycles. Additionally, DOE provides equations for calculating the actual hours for the cooling, heating, and collective shoulder seasons corresponding to any cooling and heating load hour combination.

As noted above, it is not technically feasible to use SEER and HSPF to account for the off-mode energy use. SEER and HSPF are the seasonal performance descriptors for the cooling and heating seasons, respectively. Moreover, such changes would have a deleterious impact on the manufacturer and confuse the consumer. Air conditioners and heat pumps would no longer be comparable and their energy efficiency values would only apply to similar climactic regions (
i.e.
one specific combination of cooling season hours, heating season hours, and shoulder season hours). If these energy efficiency values were integrated, SEER would be different in Maine than in Florida for similar air conditioner design. Therefore, additional precautions would be required to make sure the manufacturer only labels the units with a “locally integrated” SEER when selling a unit. This new complexity would require the consumer to have a technically pertinent knowledge to make an informed purchasing decision.

DOE seeks comments from interested parties about off-mode power consumption, its definition, and how DOE proposes to add it to the test procedure.

15. Add Parameters for Establishing Regional Standards

Implementation of regional standards for central air conditioners and heat pumps is allowed if justified. (42 U.S.C. 6295(o)(6)(D)(i)) Before DOE can establish regional standards it must fulfill two statutory requirements: (1) That the establishment of additional regional standards will produce significant energy savings in comparison to establishing only a single national standard; and (2) that the additional regional standards are economically justified. DOE has considered regional standards from two perspectives: (1) Using the existing SEER and/or HSPF rating but setting the regional standard higher than the national standard; and (2) evaluating the

regional SEER and/or HSPF using a different algorithm and establishing a standard based on this region-specific SEER and/or HSPF. As part of its standards rulemaking, DOE is considering the merits of both alternatives. Notably, DOE does not have authority to use a performance metric other than SEER and HSPF to quantify performance, either as part of a national rating or as part of a regional rating. EER and COP, for example, cannot be used.

To consider a standard based on a region-specific SEER and/or HSPF, DOE must implement changes to the test procedure. Proposed test procedure changes are itemized below. These proposed changes were formulated based on the framework specified in EISA 2007 and from the results of the preliminary analysis conducted as part of the standards rulemaking. For that framework, section 306 of EISA 2007 permits DOE to establish up to two regional standards for cooling products in addition to the national standard. (42 U.S.C. 6295(o)(6)(B)) Further, individual States shall be placed only into a single region. (42 U.S.C. 6295(o)(6)(C)(iii)) In response, DOE has tentatively decided to limit its consideration of regional standards to cooling-dominated contiguous States and, in addition, to focus only on a region-specific SEER, not HSPF. The natural division of the cooling-dominated region is an east-west partitioning where the eastern region generically qualifies as having a hot, humid climate, where the western region may be generically categorized as hot and dry.

SEER, which has and will continue to be used to establish the national standard, is evaluated based on indoor test conditions of 80 °F db/67 °F wb. These conditions would be suitable to evaluate performance when the equipment is applied in the proposed hot-humid region. As a result, test procedure changes are not necessary to complement a potential hot-humid regional standard. As currently planned, any hot-humid regional standard would be based on the current SEER algorithm. The final SEER assigned to the hot-humid regional standard, however, could be higher than the value assigned for the national standard.

As for the proposed hot-dry region, DOE identified States that could be included in this region. These States and the basis for their selection is described in the technical support document (TSD) prepared as part of the development of the residential central air conditioners and heat pumps standards. For this region, DOE is considering the option of establishing a regional SEER standard based on a region-specific SEER rating (
i.e.,
SEER or SEER Hot-Dry (SEER-HD)). The subsections that follow discuss test procedure elements that offer mechanisms for capturing equipment performance in a climate that differs from the average climate represented in the national SEER rating. Until DOE finalizes the list of States in the targeted region, some numbers and inputs are subject to change.

a. Use a Bin Method for Single-Speed SEER Calculations for the Hot-Dry Region and National Rating

The bin calculation structure currently used in the DOE test procedure for calculating the SEER of two-capacity and variable-speed systems accounts for the effects of outdoor db temperature (including a shift in the frequency of occurrence), the equipment sizing criteria, and an alternative building load profile. The bin calculation method allows a mechanism to evaluate the relative impact of installing an air conditioner or heat pump in different climates, including a hot climate.

The simple short-cut equation provided in the DOE test procedure for rating most single-speed systems typically yields a SEER value that is close to the SEER value obtained using the temperature bin

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2010-12271. Public record. Not legal advice.